The present invention relates to a separator for separating windings in an electrical apparatus.
Electrical apparatuses such as motors, generators and transformers generally comprise electrical windings wound on an iron core. The individual wires in the windings are electrically insulated by means of an outer insulation layer, which is typically enamel. However faults may develop in the outer insulation layer either due to the manufacturing process, or due to stresses imposed on the wires during construction or use of the apparatus.
Many electrical machines are constructed with overlapping groups of windings. For example, in a three phase motor or generator each phase many have one or more groups of windings, and each group may overlap another group. In such a machine, overlapping groups of windings may be at different electrical potentials. Any faults in the insulation in the wires could then lead to arcing between the groups. This would make the machine inefficient and could lead to the eventual destruction of the machine.
In order to prevent arcing between groups of windings, it is known to insert electrically insulating composite paper between the groups of windings. This composite paper typically comprises layers of Aramid and Mylar materials in varying thicknesses, depending on the physical and electrical requirements of any given application.
In electrical machines heat tends to be generated through, amongst other things, resistance in the windings and losses in the iron. The machine rating is often determined by the actual temperature rise of the machine, and thus the cooling efficiency of the construction may help to determine the rating of the machine.
A problem which has been identified in machines which use composite paper between groups of windings is that the paper may reduce the cooling efficiency of the machine. This is firstly because the exposed surface area of the windings may be reduced, and secondly because air flow through the windings may be restricted.